1. Field of the Invention
The invention relates generally to a vehicle integrated-control apparatus and a vehicle integrated-control method. More specifically, the invention relates to refinements made to a function of monitoring a drive source of a vehicle in a vehicle integrated-control apparatus and method that controls control units of the vehicle in an integrated-manner.
2. Description of the Related Art
In recent years, almost all the vehicle controls are electronically performed. For example, the operating states of an accelerator pedal and a brake by a driver are detected by respective sensors, and various control units are driven based on the values detected by these sensors. For example, when the engine control is performed, an accelerator pedal operation amount achieved by the driver, namely, an accelerator angle is detected by, for example, an acceleration stroke sensor, and a target throttle angle is calculated based on the accelerator angle. Then, a throttle valve is opened or closed by driving a throttle motor based on the target throttle angle calculated. In such electronic throttle control, the throttle angle is controlled based on the accelerator pedal operation amount. As a result, the engine drive control is smoothly performed based on a driving force desired by the driver.
Also, in the electronic throttle control, a function of monitoring the accuracy of electronic control, that is, a function of monitoring whether an error is present in a calculation is employed. For example, an electronic control unit for a vehicle described in Japanese Patent Application Publication No. JP-A-2003-254094 sets an upper limit and a lower limit of the target throttle angle calculated based on the accelerator angle, and monitors whether an actual throttle angle is within the range between the upper limit and the lower limit. If the actual throttle angle is out of the range, the upper limit or the lower limit is used instead of the actual throttle angle. As a result, even if a calculation error occurs, the throttle angle is controlled within the appropriate allowable range. Accordingly, an inappropriate increase in an output from the engine can be avoided.
In recent years, various control units that control the behavior of a vehicle are mounted in the vehicle to smoothly operate the vehicle and alleviate a burden placed on the driver by driving the vehicle. The control units individually provide instructions, for example, driving force instructions, torque instructions, and throttle angle instructions, to an engine ECU. The engine ECU controls engine power to follow these instructions. Examples of the control units that control the behavior of the vehicle include control units that instruct the engine ECU to output power other than the power requested by depression of the accelerator pedal by the driver, when the cruise control is performed or when the vehicle is running on an uphill slope. In this case, these multiple control units are controlled in an integrated-manner by an integrated-control apparatus. The integrated-control apparatus is provided with not only the instruction concerning the driving force set based on the accelerator angle but also instructions from various driving force instruction sources such as a control unit that calculates a driving force based on set contents of the above-mentioned cruise control and reflects the driving force on the control; a control unit that calculates a driving force that needs to be added to run on an uphill slope and that reflects the driving force on the control; and a control unit that adjusts a driving force in order to suppress side skid of a wheel. The integrated-control apparatus then determines the actual throttle angle by appropriately coordinating the instruction values from the control units. Accordingly, the linkage between the accelerator angle and the throttle angle, which usually correspond to each other, weakens. This reduces reliability of monitoring the actual throttle angle using the allowable range for the target throttle angle calculated based on the accelerator angle.